Experimental and Modelling Study of a Dual-Layer NH3 Slip Monolith Catalyst for Automotive SCR Aftertreatment Systems

The approach to the development of a chemically and physically consistent mathematical model of ASC dual-layer (SCR + PGM) washcoated monolith converters is herein presented. Steady-state and transient kinetic runs were performed over each one of the two ASC components (SCR and PGM) in the form of powders and also over the two mixed powdered catalysts, thus acquiring information on the interactions between the SCR and the PGM catalytic chemistries. Global kinetic models were fitted to the SCR and to the PGM catalyst data, and validated against experiments performed over both washcoated single-layered SCR and PGM monoliths and over a full dual-layer ASC honeycomb catalyst (SCR layer on top). It was found that the dual-layer (SCR + PGM) ASC architecture grants increased N₂ selectivities compared to a PGM-only washcoat.     

Overlapping ATP2C1 and ASTE1 Genes in Human Genome: Implications for SPCA1 Expression?

The ATP2C1 gene encodes for the secretory pathway calcium (Ca²⁺)-ATPase pump (SPCA1), which localizes along the secretory pathway, mainly in the trans-Golgi. The loss of one ATP2C1 allele causes Hailey-Hailey disease in humans but not mice. Examining differences in genomic organization between mouse and human we speculate that the overlap between ATP2C1 and ASTE1 genes only in humans could explain this different response to ATP2C1 dysregulation. We propose that ASTE1, overlapping with ATP2C1 in humans, affects alternative splicing, and potentially protein expression of the latter. If dysregulated, the composition of the SPCA1 isoform pool could diverge from the physiological status, affecting cytosolic Ca²⁺-signaling, and in turn perturbing cell division, leading to cell death or to neoplastic transformation.     

Spectroscopic ellipsometry analyses of thin films in different environments: An innovative “reverse side” approach allowing multi angle measurements

An innovative ellipsometer sample holder has been designed and tested in order to measure thin films optical properties under different environments and so infer the porosity through effective medium approximation models. Compared to commercial cells that require a fixed angle of incidence or a cell with a cylindrical geometry, we present a simple cell in which the sample is mounted in “reverse side”, allowing multiple angle analyses without the need for cell windows. Standard ellipsometry measurements are compared to the “reverse side” approach in order to confirm the feasibility of this new procedure, obtaining the same refractive index dispersion curves in both cases. Then different samples have been tested in “reverse side” under different environments to measure porosity. The multiangle approach has been found useful to improve the fitting of the experimental data by reducing both the fitting error and the correlation between parameters.     

The Melatonergic System in Mood and Anxiety Disorders and the Role of Agomelatine: Implications for Clinical Practice

Melatonin exerts its actions through membrane MT1/MT2 melatonin receptors, which belong to the super family of G-protein-coupled receptors consisting of the typical seven transmembrane domains. MT1 and MT2 receptors are expressed in various tissues of the body either as single ones or together. A growing literature suggests that the melatonergic system may be involved in the pathophysiology of mood and anxiety disorders. In fact, some core symptoms of depression show disturbance of the circadian rhythm in their clinical expression, such as diurnal mood and other symptomatic variation, or are closely linked to circadian system functioning, such as sleep-wake cycle alterations. In addition, alterations have been described in the circadian rhythms of several biological markers in depressed patients. Therefore, there is interest in developing antidepressants that have a chronobiotic effect (i.e., treatment of circadian rhythm disorders). As melatonin produces chronobiotic effects, efforts have been aimed at developing agomelatine, an antidepressant with melatonin agonist activity. The present paper reviews the role of the melatonergic system in the pathophysiology of mood and anxiety disorders and the clinical characteristics of agomelatine. Implications of agomelatine in “real world” clinical practice will be also discussed.     

Molecular dynamics characterization of crystalline and amorphous TiSi2 phases

Molecular dynamics simulations by a tight binding potential provide new interesting information on the ground state properties of the TiSi₂ phases. In particular, we have compared some structural, elastic, thermodynamic and electronic properties of the C49, the C54 and the amorphous phases. It turns out that the C49 structure is much softer than the C54, also displaying a melting temperature some 300–400 K below the one for the C54, in agreement to very recent experimental results. The amorphous phase is energetically and structurally more akin to the C49 than to the C54 phase. On the basis of these results we suggest the higher formation kinetics of the former to be related to an intrinsic advantage in the growth stage.     

Recovery of tartaric acid from industrial enological wastes

The recovery of tartaric acid (TA) from three industrial enological wastes: (i) cream of tartar, (ii) lees, and (iii) eluates from the regeneration of anion exchange resins used for the production of grape liquid sugar, was studied. Recovery of TA ranged between 58 and 99%, the highest being from cream of tartar. The level of addition of calcium salts is important to improve the recovery of calcium tartrate from lees and eluates. A significant inverse correlation between TA recovery and the percentage of organic acids, except for tartaric acid, was found; this index may help to optimize the level of calcium addition. Enological eluates would represent a commercial source of malic acid (recovery of 51%). © 2001 Society of Chemical Industry     

Non-Conventional Techniques for the Study of Phase Transitions in NiTi-Based Alloys

Differential scanning calorimetry and electrical resistance measurements are the two most common techniques for the study of the phase transition path and temperatures of shape memory alloys (SMA) in stress-free condition. Besides, it is well known that internal friction measurements are also useful for this purpose. There are indeed some further techniques which are seldom used for the basic characterization of SMA transition: dilatometric analysis, magnetic measurements, and Seebeck coefficient study. In this work, we discuss the attitude of these techniques for the study of NiTi-based phase transition. Measurements were conducted on several fully annealed Ni_50?x Ti₅₀Cu _x samples ranging from 3 to 10 at.% in Cu content, fully annealed at 850 °C for 1 h in vacuum and quenched in water at room temperature. Results show that all these techniques are sensitive to phase transition, and they provide significant information about the existence of intermediate phases.     

Nanoscale Mapping of Frictional Anisotropy

Friction hodographs contain all the information related to the intensity and symmetry of the friction phenomenon. We show how an atomic force microscope can be used to collect friction hodographs at the nanoscale and how to carry out data interpretation to unravel the friction–surface structure relationship. As a model system, we analyzed the basal plane of orthorhombic β-alanine single crystals, and interpreted the data in terms of a constitutive model of orthotropic friction with slip direction-dependent friction coefficients.     

Absence of ‘fragility’ and mechanical response of jammed granular materials

We perform molecular dynamic simulations of frictional non-thermal particles driven by an externally applied shear stress. After the system jams following a transient flow, we probe its mechanical response in order to clarify whether the resulting solid is ‘fragile’. We find the system to respond elastically and isotropically to small perturbations of the shear stress, suggesting absence of fragility. These results are interpreted in terms of the energy landscape of dissipative systems. For the same values of the control parameters, we check the behaviour of the system during a stress cycle. Increasing the maximum stress value, a crossover from a visco-elastic to a plastic regime is observed.